Sonic dishwasher



1968 F. A. KOCH ENDORFFER 3,413,989

SONIC DISHWASHER Filed Feb. 15, 1967 FIG.3

ATTORNEY United States Patent Olhce 3,413,989 Patented Dec. 3, 1968 ABSTRACT OF THE DISCLOSURE Dishes are carried through a washing zone of liquid subject to sonic vibration by a belt type conveyor dipping into the washing zone while the dishes are held on the conveyor by a brush yieldably conforming to the dishes and conveyor.

This invention utilizes a brush to hold dishes against the conveyor while. being carried down into and up out of the sonically activated washing liquid.

In the drawing; FIG. 1 is a longitudinal section through a dishwasher, FIG. 2 is a diagrammatic view showing the action of the brush in the washing zone and FIG. 3 is a fragmentary 'top plan view of the conveyor loaded with dishes to be washed.

The dishwasher has a tank 1 holding washing solution up to a liquid level indicated by line 2 and a frame 3 hinged at 4 carrying sprocket shafts 5, 6, 7 and 8 for a belt conveyor 9 of any suitable material such as hinged links, wire mesh, canvas, etc.

At the inlet end of the dishwasher is a sorting table 10 in which bulk food is removed and the dishes and silverware separated for loading. The silverware and other small pieces are ordinarily loaded in racks. Between the sprockets 11 and 12 the conveyor belt 9 is essentially flat and serves as a loading table. The outer surface of the conveyor belt may have cross cleats 13 to prevent slippage. The space between the cleats is large enough to receive a rack 14 or several dishes 15. The fiat loading section of the conveyor belt is above the liquid level 2.

Between the sprockets 12 and 16, the conveyor belt has a depending curveid section 17 which dips below the liquid level 2 and immerses the dishes carried by the conveyor in the detergent or washing solution. While on this section of the conveyor, the dishes are subjected to sonic vibrations from conveniently arranged transducers such as those indicated at 18 and 19. The transducer 18 is arranged between the curved section 17 of the conveyor and the return section 20 of the conveyor. The transducer 19 is arranged beneath the return section 20 of the conveyor. The purpose of the transducers 18, 19 is to transmit to the washing solution sonic vibrations of frequency and intensity sufficient to cause cavitation adjacent the surfaces of the dishes being washed. To avoid noise, the frequency is preferably ultrasonic. This cavitation has a scrubbing effect which in a few seconds dislodges all soil. The cavitation also assists the detergent in emulsifying oils and fats. The effect of the sonic waves is to scour hard or rigid surfaces. The sonic vibrations have little or no effect upon soft and yielding surfaces such as the soft bristle or other brush 21 carried by shaft 22. The brush is driven at substantially the same surface speed as the conveyor so that the brushing action is not relied upon to clean the dishes. The brush merely holds the dishes in non slipping contact against the upper surface of the conveyor belt. The bristles or other brush material,

as diagrammatically shown in FIG. 2, yield both to conform with the arcuate surface 17 of the conveyor belt and to conform to the dish indicated at 23. While the brush has a firm mechanical holding effect, keeping the dishes in place on the conveyor and preventing slippage,

it does not interfere with the sonic waves which produce the cleaning action. The sonic waves go right through soft materials such as the brush without loss of cleaning effect. The upper side of the conveyor loop enters the washing zone at a gradual'slope so the dishes remain in place on the conveyor prior to contact with the brush. The conveyor loop leaves the washing zone at a relatively steep slope and contact of the dishes with the brush is maintained substantially up to the delivery of the dishes from the conveyor.

Upon leaving the curved section 17 of the conveyor belt at sprocket 16, the dishes are delivered to a ramp consisting of spaced, inclined slats 24 from which the dishes slide down to a receiving table 25. At this stage, the dishes are subjected to downwardly and upwardly directed rinse sprays from heads 26 and. 27 which rinse the detergent solution from the dishes. A hood 28 prevents spattering. It is possible that there mayQremain on the dishes some loose particles which have not fallen off in the Washing zone and these particles will also be removed by the rinse sprays. All of the rinse waterfrom the spray heads 26, 27 may fall into the tank to freshen up the washing solution as shown, or some or all of the rinse water may be conducted to a drain. A suitable overflow or other liquid level control (not shown) limits the rise in liquid level if the rinse water falls into the tank.

Only a few seconds are required for each dish to move through the washing zone. During this time, an extremely vigorous localized scrubbing action takes place at the surfaces of the dish dislodging all food and emulsifying fats and "oils. The movement of the dishes through the washing zone is non-violent. There is no gross vibration of the dishes which could cause chipped edges. Nor are turbulent liquid currents set up which could interfere with the sonic :waves set up by the transducers. The dishes remain quietly in place on the conveyor.

The overall size and weight of the dishwasher is greatly reduced. The tank is much smaller than would be required for conventional washers. The hood 28 need cover only the rinse section. Washing causes, no splashing. Sanitation is improved. There is no recirculation of washing solution, with the danger of redeposit of food particles. The rinsing section is reduced in size because it removes the washing solution. 1

The hinging of the frame 3 permits convenient lifting of the conveyor and brush out of the washing solution for service. The single rigid frame 3 also permits a Wide choice of drives for the sprocket and brush shafts.

What is claimed as new is:

1. A dishwasher comprising a tank having a washing Zone holding awas'hing solution, transducer means for transmitting to the solution in said zone sonic waves of frequency and intensity sufficient to cause cavitation on the surfaces of dishes immersed in said solution, an endless belt conveyor loop extending across said zone, the lower side of the loop being a return loop, the upper side of the loop being a dish carrying loop having on its upper surface a dish receiving section at one side of the zone, a dish delivery section at the opposite side of the zone and an intermediate depending arcuate section dipping down into the solution at said one side of the zone and rising out of the solution at said opposite side of the zone, soft yielding means engaging the upper surface of said arcuate section and the dishes thereon in conforming contact to hold the dishes against and in nonslipping contact with said upper surface, and means for driving the belt conveyor and said soft yielding means at substantially the same surface speed, said yielding means comprising a cylindrical brush rotatable on an axis transverse to the belt.

2. The dishwasher of claim 1 in which the upper side of the loop has a generally horizontal loading section in front of said one side of the zone on which dishes may be loaded from a sorting table or the like.

3. The dishwasher of claim 2 in which the upper side of the conveyor loop enters the washing zone at a gradual slope so the dishes remain in place on the conveyor prior to contact with the brush.

4. The dishwasher of claim 1 in which the brush has bristles engaging the dishes and the arcuate section of the conveyor.

5. The dishwasher of claim 1 in which the conveyor and brush have shafts journaled in a frame hinged at one end by which the conveyor and brush may be swung up out of the washing solution for servicing.

References Cited UNITED STATES PATENTS 3,090,134 5/1963 Morrison 13473 XR 3,222,221 12/1965 Branson l3473 XR 3,357,439 12/1967 Clegg 13460 ROBERT L. BLEUTGE, Primary Examiner. 

